Phytochemical analysis and chemopreventive testing of a special “α-/β-acid free” hops extract led to the identification of isohumulones (hops iso-α-acids) as potent inducers of NAD(P)H:quinone reductase (QR) activity. CD values (concentrations required to double the specific activity of QR in Hepa1c1c7 cell culture) were in the range of 1.3 to 10.2 μg/mL, with CD value of trans-isohumulone < cis-isoadhumulone < cis-isocohumulone < cis-isohumulone (+ trans-isoadhumulone). Humulones (hops α-acids) were equally active with CD values of 3.4 to 7.6 μg/mL. However, these activities were accompanied by cytotoxicity. Cohumulinone and humulinone, oxidation products of co- and n-humulone, were inactive. We further identified isohumulones as potent inhibitors of lipopolysaccharide-induced inducible nitric oxide synthase (iNOS) activity in Raw264.7 cell culture, with IC50 values of 5.9 – 18.4 μg/mL. Humulones and humulinones were inactive at concentrations < 20 μg/mL. These results indicate that isohumulones, which are considered as the most abundant class of polyphenols in beer, should by further investigated for chemopreventive efficacy in animal models.
VerzeleM. (1986) 100-Years of hop chemistry and its relevance to brewing. Journal of the Institute of Brewing, 92, 32–48.
2.
TeuberM, SchmalreckAF. (1973) Membrane leakage in Bacillus subtilis 168 induced by the hop constituents lupulone, humulone, isohumulone and humulinic acid. Archives of Microbiology, 94, 159–171.
3.
De KeukeleireD, De CoomanL, RongH, HeyerickA, KalitaJ, MilliganSR. (1999) Functional properties of hop polyphenols. Basic Life Sciences, 66, 739–760
4.
HughesP. (2000) The significance of iso-α-acids for beer quality - Cambridge prize paper. Journal of the Institute of Brewing, 106, 271–276
5.
De KeukeleireD. (2000) Fundamentals of beer and hop chemistry. Quimica Nova, 23, 108–112.
6.
StevensJF, PageJE. (2004) Xanthohumol and related prenylflavonoids from hops and beer: to your good health!Phytochemistry, 65, 1317–1330
7.
KondoK. (2004) Beer and health: preventive effects of beer components on lifestyle-related diseases. Biofactors, 22, 303–310
8.
GerhauserC. (2005) Beer constituents as potential cancer chemopreventive agents. European Journal of Cancer, 41, 1941–1954.
9.
LeeJC, KunduJK, HwangDM, NaHK, SurhYJ. (2007) Humulone inhibits phorbol ester-induced COX-2 expression in mouse skin by blocking activation of NF-κB and AP-1: I-κB kinase and c-Jun-N-terminal kinase as respective potential upstream targets. Carcinogenesis, 28, 1491–1498.
10.
NozawaH, NakaoW, ZhaoF, KondoK. (2005) Dietary supplement of isohumulones inhibits the formation of aberrant crypt foci with a concomitant decrease in prostaglandin E2 level in rat colon. Molecular Nutrition and Food Research, 49, 772–778
11.
ShindoS, TomatsuM, NakdaT, ShibamotoN, TachibanaT, MoriK. (2002) Inhibition of aldose reductase activity by extracts from hops. Journal of the Institute of Brewing, 108, 344–347
12.
YajimaH, IkeshimaE, ShirakiM, KanayaT, FujiwaraD, OdaiH, Tsuboyama-KasaokaN, EzakiO, OikawaS, KondoK. (2004) Isohumulones, bitter acids derived from hops, activate both peroxisome proliferator-activated receptor α and γ and reduce insulin resistance. Journal of Biological Chemistry, 279, 33456–33462
13.
YajimaH, NoguchiT, IkeshimaE, ShirakiM, KanayaT, Tsuboyama-KasaokaN, EzakiO, OikawaS, KondoK. (2005) Prevention of diet-induced obesity by dietary isomerized hop extract containing isohumulones, in rodents. International Journal of Obesity (London), 29, 991–997
14.
MiuraY, HosonoM, OyamadaC, OdaiH, OikawaS, KondoK. (2005) Dietary isohumulones, the bitter components of beer, raise plasma HDL-cholesterol levels and reduce liver cholesterol and triacylglycerol contents similar to PPARalpha activations in C57BL/6 mice. British Journal of Nutrition, 93, 559–567
15.
ShimuraM, HasumiA, MinatoT, HosonoM, MiuraY, MizutaniS, KondoK, OikawaS, YoshidaA. (2005) Isohumulones modulate blood lipid status through the activation of PPAR alpha. Biochimica et Biophysica Acta, 1736, 51–60
16.
NamikoshiT, TomitaN, FujimotoS, HarunaY, OhzekiM, KomaiN, SasakiT, YoshidaA, KashiharaN. (2007) Isohumulones derived from hops ameliorate renal injury via an anti-oxidative effect in Dahl salt-sensitive rats. Hypertension Research, 30, 175–184.
17.
GerhauserC, AltA, HeissE, Gamal-EldeenA, KlimoK, KnauftJ, NeumannI, ScherfHR, FrankN, BartschH, BeckerH. (2002) Cancer chemopreventive activity of xanthohumol, a natural product derived from hop. Molecular Cancer Therapeutics, 1, 959–969.
18.
BohrG, GerhauserC, KnauftJ, ZappJ, BeckerH. (2005) Anti-inflammatory acylphloroglucinol derivatives from hops (Humulus lupulus). Journal of Natural Products, 68, 1545–1548.
19.
BiendlM, MethnerF-J, StettnerG, WalkerCJ. (2004) Brauversuche mit einem xanthohumolreichen Hopfenprodukt. Brauwelt, 144, 236–244.
VerzeleM, De KeukeleireD. (1991) Chemistry and analysis of hop and beer bitter acids. Elsevier Science Publishers B.V., Amsterdem, New York, 1–417
22.
NordLI, SorensenSB, DuusJO. (2003) Characterization of reduced iso-α-acids derived from hops (Humulus lupulus) by NMR. Magnetic Resonance in Chemistry, 41, 660–670
23.
VanhoenackerG, De KeukeleireD, SandraP. (2004) Analysis of iso-α-acids and reduced iso-α-acids in beer by direct injection and liquid chromatography with ultraviolet absorbance detection or with mass spectrometry. Journal of Chromatography A, 1035, 53–61
24.
ChadwickLR, NikolicD, BurdetteJE, OverkCR, BoltonJL, van BreemenRB, FrohlichR, FongHH, FarnsworthNR, PauliGF. (2004) Estrogens and congeners from spent hops (Humulus lupulus). Journal of Natural Products, 67, 2024–2032
25.
KhatibA, WilsonEG, KimHK, SupardiM, ChoiYH, VerpoorteR. (2007) NMR assignment of iso-α-acids from isomerised extracts of Humulus lupulus L. cones. Phytochemical Analysis, 18, 371–377.
26.
Hermans-LokkerbolACJ, VerpoorteR. (1994) Preparative separation and isolation of three α-bitter acids from hop, Humulus lupulus L, by centrifugal partition chromatography. Journal of Chromatography A, 664, 45–53.
27.
SpornMB, NewtonDL. (1979) Chemoprevention of cancer with retinoids. Federation Proceedings, 38, 2528–2534.
28.
ValkoM, LeibfritzD, MoncolJ, CroninMT, MazurM, TelserJ. (2007) Free radicals and antioxidants in normal physiological functions and human disease. International Journal of Biochemistry and Cell Biology, 39, 44–84.
29.
TagashiraM, WatanabeM, UemitsuN. (1995) Antioxidative activity of hop bitter acids and their analogues. Bioscience Biotechnology and Biochemistry, 59, 740–742.
30.
GerhauserC, KlimoK, HeissE, NeumannI, Gamal-EldeenA, KnauftJ, LiuGY, SitthimonchaiS, FrankN. (2003) Mechanism-based in vitro screening of potential cancer chemopreventive agents. Mutation Research, 523–524, 163–172.
31.
JaiswalAK. (2000) Regulation of genes encoding NAD(P)H:quinone oxidoreductases. Free Radical Biology and Medicine, 29, 254–262.
32.
EgglerAL, GayKA, MesecarAD. (2008) Molecular mechanisms of natural products in chemoprevention: induction of cytoprotective enzymes by Nrf2. Molecular Nutrition and Food Research, 52 (Suppl 1): S84–94.
33.
OhshimaH, BartschH. (1994) Chronic infections and inflammatory processes as cancer risk-factors - Possible role of nitric-oxide in carcinogenesis. Mutation Research, 305, 253–264.
34.
GerhauserC, HeissE, HerhausC, KlimoK. (2001) Potential chemopreventive mechanisms of chalcones. In: Dietary anticarcinogens and antimutagens: chemical and biological aspects Vol. 4.4, JohnsonIT, FenwickGR (Eds.), Royal Society of Chemistry, Cambridge, 189–192
35.
HeissE, HerhausC, KlimoK, BartschH, GerhauserC. (2001) Nuclear factor kappa B is a molecular target for sulforaphane-mediated anti-inflammatory mechanisms. Journal of Biological Chemistry, 276, 32008–32015
36.
Dinkova-KostovaAT, LibyKT, StephensonKK, HoltzclawWD, GaoX, SuhN, WilliamsC, RisingsongR, HondaT, GribbleGW, SpornMB, TalalayP. (2005) Extremely potent triterpenoid inducers of the phase 2 response: correlations of protection against oxidant and inflammatory stress. Proceedings of the National Academy of Sciences of the United States of America, 102, 4584–4589.
37.
YamamotoK, WangJ, YamamotoS, TobeH. (2000) Suppression of cyclooxygenase-2 gene transcription by humulone of beer hop extract studied with reference to glucocorticoid. FEBS Letters, 465, 103–106.
38.
ZhaoF, NozawaH, DaikonnyaA, KondoK, KitanakaS. (2003) Inhibitors of nitric oxide production from hops (Humulus lupulus L.). Biological & Pharmaceutical Bulletin, 26, 61–65.
39.
NozawaH, NakaoW, TakataJ, Arimoto-KobayashiS, KondoK. (2006) Inhibition of PhIP-induced mammary carcinogenesis in female rats by ingestion of freeze-dried beer. Cancer Letters, 235, 121–129.
40.
CarlH. (1997) Hops and Hop Products (Manual of good practice). EBC Technology and Engineering Forum, Nürnberg, pp. 67–68.
41.
PuseckerK, AlbertK, BayerE. (1999) Investigation of hop and beer bitter acids by coupling of high-performance liquid chromatography to nuclear magnetic resonance spectroscopy. Journal of Chromatography A, 836, 245–252
42.
HoekAC, Hermans-LokkerbolACJ, VerpoorteR. (2001) An improved NMR method for the quantification of alpha-acids in hops and hop products. Phytochemical Analysis, 12, 53–57.
43.
ProchaskaHJ, SantamariaAB. (1988) Direct measurement of NAD(P)H:quinone reductase from cells cultured in microtiter wells: a screening assay for anticarcinogenic enzyme inducers. Analytical Biochemistry, 169, 328–336.
